Pump plan: nomenclature, position reference and Magès' machining critique (15/11/1951)

In this document

Page 6: nomenclature and position reference

Page 6 presents a box entitled "REPÈRE POSITION" p. 6. Around a large plan in cross-section view of a mechanical assembly (probably a valve or a hydraulic distributor), there is a list of numerical references: on the left side, references such as 1633S, 2458S, 2071S, as well as a series of parts referenced E401.134c to E401.141c, with two mentions of "Joinfranite n°14" p. 6. On the right side, we note the reference/position pairs E401.568c / 648S, E401.560c / 2489S, E401.561c / 2513S, as well as an assembly noted "E401.770b" p. 6. At the bottom of the page, a second sketch (a part seen in perspective, cylindrical body with diagonal fitting) is accompanied by the references 2458S and E401.8176 p. 6.

Page 7: handwritten critique by Magès

Page 7 repeats the three references 648S, 2489S, 2513S above a technical diagram of a pump drawn on tracing paper, with a printed graduated ruler p. 7.

A handwritten note indicates that this pump must be replaced by a new drawing by Magès, with a "drive on the shaft" (passages partially uncertain), and specifies that a "plan in progress at the B.E.A." must replace this drawing, dated 15 November 1951 p. 7.

Magès formulates a direct judgment: "The machining of this pump is, moreover, unacceptable!" p. 7. He details two technical points:

• a) a cylinder with a diameter of 10 mm, length 58 mm, with an assembly clearance of 0.005 p. 7;
• b) grooves in the pump body, qualified with an uncertain term p. 7.

The note is dated "Le 15/11/51" and bears an illegible signature preceded by the mention "M." p. 7.

Context

The B.E.A. (Bureau d'Études Automobiles) is, in the Citroën organisation of the time, the department in charge of mechanical design — a framework outside the document that helps to situate this internal work note.

These pump plans date from the period when Paul Magès was developing the hydropneumatic suspension, a system on which he had been working since his first plans of 17 February 1944 and which would equip the Citroën DS presented on 6 October 1955. The machining precision requirements mentioned here (clearances of a few hundredths of a millimetre) are typical of the high-precision hydraulic components necessary for this type of system, but this link is not made explicit in the document itself.

Archivist's perspective

This double page concretely illustrates the quality control work carried out by Magès on subcontractors or machining workshops: he does not just design, he verifies and sanctions the actual manufacturing of the parts p. 7. This verification role is part of the function he then occupied at Citroën, where he evolved as a self-taught person from technical writer to deputy head of the Super-Control (Draft letter from Paul Magès to Mr. Sarre and interview plan of 11 May 1969).

The mention of a drawing replacement "at the B.E.A." on the same day suggests a rapid iterative process between the observation of a defect and the correction of the plan — probably revealing the rigour demanded by Magès regarding hydraulic tolerances.

This document is part of a coherent series on this same subject, to be compared with the Handwritten note by Magès on the replacement of the pump drawing and its machining defects (15/11/51), written on the same day, and the Plan E401.144c-147c with handwritten observations by Magès on the machining of the pump, dated a few weeks earlier, which together document a difficult development phase for this pump.